The invention discloses a C-shaped preembedding channel multi-head welding machine which comprises a multi-head welding machine body. The C-shaped preembedding channel multi-head welding machine is characterized in that guide rails are arranged in front of welding heads of the multi-head welding machine body, and a welding part fixing support is arranged on the guide rails and can move transversely on the guide rails. Due to the multiple welding of welded parts on C-shaped channel steel by the C-shaped preembedding channel multi-head welding machine, a large number of welded part can be welded. The deformation of the C-shaped channel steel is reduced, the investment of the equipment is reduced and the equipment is convenient to debug.